Randomized Algorithms for Mixed Matching and Covering in Hypergraphs in 3D Seed Reconstruction in Brachytherapy

Brachytherapy is a method developed in the 1980s for cancer radiation in organs like prostate, lung, or breast. At the Clinic of Radiotherapy (radiooncology), Christian Albrechts University of Kiel, among others, low dose radiation therapy (LDR therapy) for the treatment of prostate cancer is applied, where 25-80 small radioactive seeds are implanted in the affected organ. For the quality control of the treatment plan the locations of the seeds after the operation have to be checked. This is done by taking usually 3 X-ray photographs from three different angles (so-called 3-film technique). On the films the seeds appear as white lines. To determine the positions of the seeds in the organ the task now is to match the 3 different images (lines) representing the same seed. In this paper we first model the seed reconstruction problem as a minimum-weight perfect matching problem in a hypergraph and based on this as an integer linear program. To solve this integer program, an algorithm based on the so-called randomized rounding scheme introduced by Raghavan and Thompson (1987) is designed and applied. This algorithm is not only very fast, but accessible at least in part for a mathematical rigorous analysis. We give a partial analysis of the algorithm combining probabilistic and combinatorial methods, which shows that in the worst-case the solution produced is in some strong sense close to a minimum-weight perfect matching

Long-term prognostic and predictive factors in hormone receptor positive breast cancer

The breast cancer survival in Sweden is good (almost 90 % 5-year relative survival) and has increased over time. For women with hormone receptor negative tumors, most relapses occur within the first 5 years after diagnosis. Thereafter the recurrence risk decreases rapidly. For women with estrogen receptor positive (ER+) tumors the annual risk for late recurrences is 1 – 2 %, even after 5 years of endocrine therapy. This risk accumulates so that approximately 25 % of the patients that are recurrence-free after five years from diagnosis may experience a relapse within further 15 years of follow-up. The relatively high long-term risk calls for identification of prognostic and predictive markers with long-term effect. Though, the number of such markers with proven significance is limited. Of the clinical characteristics, only nodal status and to some extent tumor size and tumor grade have been shown to have long-term prognostic value. In this thesis, we propose long-term prognostic and predictive markers for breast cancer. In paper I, we suggest the protein v-akt murine thymoma viral oncogene homologue 2 (AKT2) as a long-term prognostic marker among patients with ER+ tumors. In our study, besides nodal status, AKT2 was the only factor with long-term prognostic value. This is in accordance with some other studies, though we also showed that the significance of AKT2 was limited to ER+ tumors and that the impact increased with higher ER expression. Approximately 75 – 85 % of the ER+ tumors are also progesterone receptor positive (PR+). ER+/progesterone receptor negative (PR-) tumors are considered to be more aggressive and patients with such tumors are often treated with chemotherapy. In this group, more specific subgroups for targeted therapy are needed. Whereas ER has long been established as a predictive factor regarding tamoxifen benefit, the role of PR has not been clarified to date. In paper II, we showed that PR status adds predictive value to ER considering the long-term benefit from tamoxifen. In paper III, we aimed to identify new prognostic markers among patients with ER+ tumors. Systemically untreated patients with ER+/PR- tumors and high expression of the Ras-related protein RAB6C (RAB6C) had reduced distant recurrence rate. Therefore, we suggest RAB6C as a candidate marker for subgroup division among patients with ER+/PR- tumors. According to the results from paper II, there might be subgroups of patients with ER+/PRtumors that do benefit from tamoxifen. The aim of paper IV was to identify such subgroups. Here, we suggest that patients with ER+/PR- tumors and low RAB6C expression do benefit from tamoxifen. The results from this thesis may encourage further studies for more specific subgroup divisions. Such studies may lead to changes in the management program, where some patients with ER+ tumors should receive prolonged or more intense treatment and others reduced treatment based on the pathological markers AKT2, PR and RAB6C.

Patient reported experiences of Swedish patients being investigated for cancer during the Covid-19 pandemic

Background: Patient reported experiences in individuals being investigated for cancer have been recorded in a nationwide survey in Sweden, providing an opportunity to assess the impact of the Covid-19-pandemic. Material and Methods: Questionnaires from 45920 patients were analyzed to assess the experience of being investigated for cancer. Data from before the Covid-19-pandemic (2018–2019) was compared to data acquired during the pandemic (2020–2021), using chi-square and Wilcoxon rank sum tests. Both, patients who were cleared from suspicion of cancer and those who were diagnosed with cancer were included. Results: Fewer patients in total visited health services during the pandemic. However, patients that did seek help did so to a similar extent during as prior to the pandemic. Patient waiting time was perceived to be shorter during the pandemic and judged as neither too long nor too short by most patients. The emotional support to patients improved during the pandemic, whereas the support to next of kin declined. A majority of patients received the results from the investigation in a meeting with the physician. Although there was a preference for receiving results in a meeting with the physician, the pandemic has brought an increasing interest in receiving results by phone. Conclusion: Swedish cancer healthcare has shown resilience during the Covid-19-pandemic, maintaining high patient satisfaction while working under conditions of extraordinary pressure. Patients became more open to alternatives to physical “in person” health care visits which could lead to more digital visits in the future. However, support to significant others demands special attention

Copyright: Elsevier

Akt2 expression is associated with good longter

Progesterone receptor positivity is a predictor of long-term benefit from adjuvant tamoxifen treatment of estrogen receptor positive breast cancer

The independent predictive information from progesterone receptor (PgR) positivity for breast cancer treated with tamoxifen has been questioned after an overview by the Early Breast Cancer Trialists Collaborative Group (EBCTCG). However, the studies in the overview were to a large content performed before modern PgR immunohistochemistry (IHC) was developed. We therefore investigated the predictive value of PgR determined with IHC in estrogen receptor (ER)-positive tumors from patients participating in the Stockholm trial of adjuvant tamoxifen therapy. The Stockholm Breast Cancer Study Group conducted a randomized trial during 1976 through 1990 comparing adjuvant tamoxifen versus control. The patients were stratified according to tumor size and lymph node status in high-risk and low-risk groups. In this study, we evaluated 618 patients with ER-positive "low-risk" breast cancer (size aecurrency sign 30 mm, lymph node-negative) for whom PgR was determined by IHC at one pathology laboratory. The median time of follow-up was 21 years. Patients with ER-positive tumors that were also PgR-positive by IHC did benefit from tamoxifen, while we could not show any long-term benefit for those with tumors positive for ER only (recurrence rate ratio 0.43, 95 % CI 0.29-0.62 and 0.87, 95 % CI 0.52-1.46, respectively). We further investigated the influence of different levels of PgR positivity on recurrence risk. The results show that at all receptor levels with aeyen10 % stained PgR-positive cells, the patients did benefit from tamoxifen. There was no clear linear trend in benefit with increasing proportion of stained cells. PgR positivity determined by IHC is a marker indicating long-term benefit from adjuvant tamoxifen in patients with ER-positive tumors.Funding Agencies|Swedish Cancer Society; Swedish Breast Cancer Association; Cancer Research Foundations of Radiumhemmet; Cancer Society in Stockholm; King Gustav V Jubilee Clinical Research Foundation; County Council of Ostergotland; Onkologiska Klinikernas i Linkoping Forskningsfond</p

Prediction of Non-Sentinel Node Metastasis in Breast Cancer - A Population-Based Study

Background It is debated if all breast cancer (BC) patients with sentinel lymph node metastasis need axillary lymph node dissection (ALND). Based on clinical and biological factors, we explore a statistical model for predicting non sentinel node metastasis (non-SNm) in patients with positive SN (SN+). Methods We obtained data on patients from the Swedish National Quality Register for BC patients operated Jan 2008 - May 2012. Pearson´s chi-squared test was performed to compare clinical data with presence of non-SNm. The risk of non-SNm, estimated as odds ratio (OR), was calculated with multivariable logistic regression analysis and the results were visualized with a nomogram. Receiver operating characteristic (ROC) analysis was used to evaluate the discriminatory ability of the regression model (Prisk) in predicting non-SNm. Results Out of 5382 patients with SN+, 3181 had macro metastases at sentinel node biopsy and were treated with ALND. The non-SNm was statistically significant correlated to the proportion of SN+ (OR increased from 1.41 to 3.75 with raised proportion, p&lt;0.001), tumor size (OR= 1.70, p&lt;0.001), LVI-lymphovascular infiltration (OR= 1.63, p&lt;0.001), HER2 expression (OR= 1.49, p=0.004) and multifocality (OR= 1.28, p=0.04). A cut-off value of 0.3 for Prisk based on the logistic regression model, yielded a sensitivity of 83.2% and specificity of 34.7 % in predicting non-SNm. The results were visualized with a nomogram where the proportion of SN+ was the most important factor. Conclusion In this study we present a statistical score encompassing BC biology with good sensitivity and acceptable specificity that may be used in predicting non-SNm as a complement to traditional staging system used in clinical assessment of BC

Improved survival for women with stage I breast cancer in south-east Sweden : A comparison between two time periods before and after increased use of adjuvant systemic therapy

Purpose. Continuous minor steps of improvement in the management of breast cancer have resulted in decreased mortality rates during the last decades. The aim of this study was to compare the clinical outcome of patients with stage I breast cancer diagnosed during two time periods that differed with respect to adjuvant systemic therapy. Material and methods. The studied population consisted of all women 60 years of age, who were diagnosed breast cancer stage I between 1986 and 1999 in south-east Sweden, a total of 1 407 cases. The cohort was divided into two groups based on the management programmes of 1986 and 1992, hereafter referred to as Period 1 and Period 2. Before 1992 the only adjuvant systemic therapy recommended was tamoxifen for hormone receptor positive patients aged 50 years or older. During Period 2 the use of adjuvant treatment was extended to younger patients at high risk, identified by a high tumour S-phase fraction, with either hormonal or cytotoxic treatment. Results. The estimated distant recurrence-free survival rate was significantly higher during Period 2 than during Period 1 (p = 0.008). Subgroup analysis showed that the most evident reduction of distant recurrence risk was among hormone receptor-negative patients (HR = 0.58, 95% CI 0.31-1.09, p = 0.09) and among patients with a high tumour S-phase fraction (HR = 0.53, 0.30-0.93, p = 0.028). The risk reduction between the periods was still statistically significant in multivariate analysis when adjusting for different tumour characteristics and treatment modalities, indicating an influence of other factors not controlled for. One such factor may be the duration of tamoxifen treatment, which likely was more frequently five years during Period 2 than during Period 1. Conclusions. We conclude that the causes of the increase in distant recurrence free survival for women with breast cancer stage I are complex. The results support though that high-risk subgroups of stage I breast cancer patients did benefit from increased use of systemic therapy as a consequence of an updated management programme.This is an electronic version of an article published in: Patrik Johansson, Helena Fohlin, Lars-Gunnar Arnesson, Monika Dufmats, Kerstin Nordenskjoeld, Bo Nordenskjöld and Olle Stål, Improved survival for women with stage I breast cancer in south-east Sweden: A comparison between two time periods before and after increased use of adjuvant systemic therapy, 2009, ACTA ONCOLOGICA, (48), 4, 504-513. ACTA ONCOLOGICA is available online at informaworldTM: http://dx.doi.org/10.1080/02841860902718754 Copyright: Taylor &amp; Francis http://www.tandf.co.uk/journals/default.aspGroup Author(s):The South-East Sweden Breast Cancer Study GroupAnnika Malmström, Linköping University</p

Akt2 expression is associated with good long-term prognosis in oestrogen receptor positive breast cancer

Introduction Akt is a signalling modulator for many cellular processes, including metabolism, cell proliferation, cell survival and cell growth. Three isoforms of Akt have been identified, but only a few studies have concerned the isoform-specific roles in the prognosis of breast cancer patients. The aim of this study was to investigate the prognostic value of v-akt murine thymoma viral oncogene homologue 1 (Akt1) and v-akt murine thymoma viral oncogene homologue 2 (Akt2) in oestrogen receptor positive (ER+) and oestrogen receptor negative (ER–) breast cancer with long-term follow-up. Material and methods The expression of Akt in tumour tissue was analysed with immunohistochemistry in a cohort of 272 postmenopausal patients with stage II breast cancer. The median follow-up time was 19 years. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using the Cox’s proportional hazards model. Results The risk of distant recurrence was reduced for patients with ER+ tumours expressing Akt2 compared to patients with no Akt2 expression (HR = 0.49, 95% CI 0.29–0.82, p = 0.007). When adjusting for important clinical tumour characteristics and treatment, Akt2 was still an independent prognostic factor (HR = 0.38, 95% CI 0.21–0.68, p = 0.001) and the association remained long-term. The prognostic value of Akt2 increased with higher oestrogen receptor levels from no effect among patients with ER– tumours to 68% risk reduction for the group with high ER-levels (P for trend = 0.042). Akt1 showed no significant prognostic information. Conclusion Our results indicate that Akt2 expression is associated with a lower distant recurrence rate for patients with ER+ tumours and that this association remains long-term. The prognostic value of Akt2 increases with higher oestrogen receptor expression, motivating further mechanistic studies on the role of Akt2 in ER+ breast cancer.Funding Agencies|Swedish Cancer Society||Swedish Research Council||</p

RAB6C is an independent prognostic factor of estrogen receptor-positive/progesterone receptor-negative breast cancer

The majority of breast cancer tumors are estrogen receptor-positive (ER+) and can be treated with endocrine therapy. However, certain patients may exhibit a good prognosis without systemic treatment. The aim of the present study was to identify novel prognostic factors for patients with ER breast cancer tumors using gene copy data, and to investigate if these factors have prognostic value in subgroups categorized by progesterone receptor status (PR). Public data, including the whole genome gene copy data of 199 systemically untreated patients with ER+ tumors, were utilized in the present study. To assess prognostic value, patients were divided into two groups using the median gene copy number as a cut-off for the SNPs that were the most variable. One SNP was identified, which indicated that the Ras-related protein Rab-6C (RAB6C) gene may exhibit prognostic significance. Therefore, RAB6C protein expression was subsequently investigated in a second independent cohort, consisting of 469 systematically untreated patients (of which 310 were ER+) who received long term follow-up. In the public data set, a distant recurrence risk reduction of 55% was determined for copy numbers above the median value of RAB6C compared with numbers below [multivariable adjusted hazard ratio (HR), 0.45; 95% CI 0.28-0.72; P=0.001)]. It was also more pronounced in the ER+/PR- subgroup (HR, 0.15; 95% CI, 0.05-0.46; P=0.001). In the second cohort, patients of the ER+/PR- subgroup who exhibited high RAB6C expression had a reduced distant recurrence risk (HR, 0.17; 95% CI, 0.05-0.60; P=0.006). However, this was not identified among ER+/PR- tumors (HR, 1.31; 95% CI, 0.69-2.48; P=0.41). The results of the present study indicated that RAB6C serves as an independent prognostic factor of distant recurrence risk in systemically untreated patients with an ER+/PR- tumor.Funding Agencies|Swedish Cancer SocietySwedish Cancer Society [17-0479]; Cancer Research Foundations of Radiumhemmet; Cancer Society in Stockholm; King Gustav V Jubilee Clinical Research Foundation [181093]; Onkologiska klinikerna i Linkopings forskningsfond [2016-06-21]; ALF grants Region Ostergotland [LIO-795201]; County Council of Ostergotland [LIO-625491]</p